NERVOUS SYSTEM 59 



emerge from the surface of the brain on the outer 

 sides of the crura cerebri. 



B. Cerebellum. 



1. The Cerebellum is the large unpaired portion 

 of the brain lying just posterior to the cerebral 

 hemispheres. The dorsal surface is marked by nu- 

 merous parallel grooves. It consists of two lateral 

 lobes or hemispheres, and a median portion or 

 vermis. It is connected with the rest of the brain 

 by three pairs of fibrous bands or crura. The first 

 pair are the superior peduncles. They connect the 

 cerebellum with the corpora quadrigemina. The 

 second and largest pair form the lateral continua- 

 tions of the pons Varolii. They are known as 

 the middle peduncles. The third pair, the inferior 

 peduncles, connect the cerebellum with the me- 

 dulla oblongata. (Plate VII., A and c.) 



2. The Pons Varolii is the broad, transverse band 

 of fibres on the ventral side of the brain, con- 

 necting the two sides of the cerebellum. (Plate 

 VII., A.) 



3. The fifth pair of cranial nerves, the Trigeminal, 

 arise by two roots on either side of the pons Va- 

 rolii. (Plate VII., A.) 



4. The sixth pair of cranial nerves, the Abducens, 

 leave the surface of the brain at the posterior 

 margin of the pons near the mid-ventral line. 

 (Plate VII., A.) 



5. The Anterior Pyramids are the two longitudinal 



